Im terrible at this so if im wrong sorry I think ur legs are a bit far back and yes heels down also in the first pick you look like ur looking to the side (may not be) and if you are that's ok coz you have to look to the next jump but just watch out for ur body sloping that way too as that's what it looks like in the pick
I really like your release..you're really giving your horse freedom, which I think is pretty important. =)
But yes, like most people have pointed out..keep your lower leg forward and streeettcch your back! Try to be as tall as possible..you look a little hunched in some of the pics.
Pretty nice overall, tho!